The present invention relates to composite structures, and more particularly to composite panels and methods for making such panels.
Current aircraft floor systems incorporate thin metallic or composite prepreg skin materials adhesively bonded to either a metallic or non-metallic honeycomb core. Current metallic aircraft floor systems require minimal tooling and have high tolerances, but may not achieve the weight benefits of composite floor systems.
Current aircraft composite floor system floor panels utilize a honeycomb core material with pre-cured fiberglass or prepreg composite skins bonded thereto in a large heated press or autoclave. Local hard points and edge closeouts are typically accomplished with an epoxy potting compound. The floor panels may require relatively complicated and labor intensive process steps including: pre-curing of the inboard and outboard skins; cutting, machining, and forming of the honeycomb core; local densification of the honeycomb core at attachment hard points and edge closeouts; preparation of the skins and core assembly for bonding; assembly of the pre-cured skins, lay-up of film adhesive layers for bonding; curing of the assembled skins, adhesive, and core; secondary machining, densification, and splicing operations of the honeycomb core material; and multiple processing cycles in an autoclave, oven or press, to complete fabrication of an individual panel.
Although composite floor systems are generally lighter in weight than metallic floor systems, composite floor systems may be more expensive and labor intensive to manufacture.
Moreover, usage of honeycomb core structures in rotary-wing aircraft floor systems may suffer inherent moisture absorption due to the open cell structure. Such moisture absorption may result in increased weight and a resultant performance degradation over a prolonged service period.
Accordingly, it is desirable to provide panels suitable for use in an aircraft floor system that are lighter in weight and manufactured in fewer steps relative to current panels, yet meet or exceed design requirements therefor.